Carbon-nitrogen place exchange on NO exposed beta-Mo2C

Area of Science:

• Surface Science
• Materials Chemistry
• Catalysis

Background:

• Understanding the surface interactions of transition metal carbides is crucial for catalytic applications.
• The behavior of nitrogen and oxygen on beta-molybdenum carbide (beta-Mo(2)C) surfaces under reaction conditions requires detailed investigation.

Purpose of the Study:

• To investigate the interplay between atomic nitrogen, carbon, and oxygen on beta-Mo(2)C surfaces.
• To elucidate the surface chemistry and structural changes occurring during NO adsorption and subsequent reactions.
• To determine the fate of displaced carbon and the effect of nitrogen incorporation on oxygen dissolution.

Main Methods:

• Synchrotron X-ray Photoelectron Spectroscopy (XPS) for high-resolution surface analysis.
• Reflectance Absorbance Infrared Spectroscopy (RAIRS) for identifying surface species.
• Thermal Desorption Spectroscopy (TDS) to study desorption kinetics and temperatures.

Main Results:

• Atomic nitrogen was observed to displace interstitial carbon onto the beta-Mo(2)C surface.
• Displaced carbon undergoes thermal burnoff at approximately 890 K.
• Nitrogen incorporation into interstitial sites inhibits the dissolution of oxygen into the bulk.
• Surface oxo and terminal oxygen species were identified using RAIRS.

Conclusions:

• Atomic nitrogen plays a key role in modifying the surface composition of beta-Mo(2)C by displacing carbon.
• The thermal stability of the carbide is influenced by nitrogen and oxygen interactions.
• The findings provide insights into the surface chemistry relevant for catalytic processes involving Mo(2)C.